1. Field of the Invention
The present invention relates to a semiconductor manufacturing apparatus for manufacturing a semiconductor device, and more particularly, to a heat treatment technology of performing activation annealing or repair annealing of defects and oxidation of the surface after doping of impurities performed in order to conductively control a semiconductor substrate.
2. Description of the Related Art
In recent years, introduction of a new material having a wideband gap such as silicon carbide (hereinafter, referred to as SiC) as a substrate material of a power semiconductor device has been expected. SiC which is a wideband gap semiconductor has a more excellent physical property than silicon (hereinafter, referred to as Si) such as a high insulation breakdown electric field, a high saturated electron velocity, and high thermal conductivity. In that the wideband gap semiconductor, SiC is a high insulation breakdown electric field material, a device can be thinned or doped with high concentration, and a device having high resisting pressure and low resistance can be fabricated. Further, since a band gap is large, thermal excitation electrons can be suppressed and a stable operation can be achieved at a high temperature in that a heat dissipation ability is high by high thermal conductivity. Accordingly, when the SiC power semiconductor device is implemented, significant efficiency improvement and enhanced performance of various power and electric equipments such as devices for power transportation and conversion, an industrial power device and home electric appliances can be expected.
A process of manufacturing various power devices by using SiC in the substrate is substantially the same as that of a case in which Si is used in the substrate. However, a heat treatment process may be mentioned as a significantly different process. The typical heat treatment process is activation annealing after ion implantation of impurities, which is performed for the purpose of conductively controlling the substrate. In the case of a Si device, the activation annealing is performed at a temperature in the range of 800 to 1200° C. Meanwhile, in the case of SiC, a temperature in the range of 1200 to 2000° C. is required due to a material characteristic thereof.
As an annealing apparatus for the SiC substrate, for example, a resistance heating furnace disclosed in Japanese Patent Application Laid-Open Publication No. 2009-32774 has been known. Further, in addition to the resistance heating furnace type, for example, an induction heating type annealing apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 2010-34481 has been known. Japanese Patent Application Laid-Open Publication No. 2009-231341 discloses a method of installing a cover exposing SiC in a part facing the SiC substrate as a method for suppressing SiC surface roughness by annealing. Japanese Patent Application Laid-Open Publication No. 2010-517294 discloses an apparatus for heating a wafer through a metallic sheath by atmospheric pressure plasma generated by a microwave.